Toward a Home-Based Systemfor Improving Functional Hand and

Arm Movement Recovery

David Reinkensmeyer

Department of Mechanical and Aerospace Engineering

University of California at Irvine

Robert Sanchez, Punit Shah, Vu Le, Sandhya Rao, Jim Bobrow, Steve Cramer @ UCI

Sarah Housman @ RIC

Working HypothesisA non-robotic (i.e. passive) device that can:

• allow practice of functional movements• move in a 3-D workspace similar to the upper

extremity • relieve the weight of the arm• integrate hand and arm movement• provide quantitative feedback of movement

abilityWill be a safe, useful tool for assisting with movement

training of severely weakened stroke patients

T-WREX Design

• Based on WREX (Wilmington Robotic Exoskeleton), (Rahman et al., 2000)*.– Counterbalances weight of arm using

rubber bands and four-bar mechanisms

• T-WREX (Training-WREX) Modifications:– Adult Sized– Stronger– Sensorized (arm and handgrip)– Easily Adjustable– Designed for Manufacturability– Total Manufacturing Cost:

• $8,000*Rahman T, Sample W, Seliktar R, Alexander M, Scavina M (2000) A body-powered functional upper limb orthosis. Journal of Rehabilitation Research and Development 37:675-680.

WREX

T-WREX

T-WREX Device Testing

• Phase I: Effect of T-WREX on movement ability, measured in a single session

• Phase II: Pilot study of training effects

• Phase III: Randomized, controlled trial of T-WREX’s efficacy (just started)

Phase I Testing*

Research questions:• How well does the counterbalance work for

stroke patients?• Can stroke patients move better while they

are wearing the device?

*Sanchez R, Shah P, Liu J, Rao S, Smith R, Cramer S, Rahman T, Bobrow JE, Reinkensmeyer D (2004) Monitoring Functional Arm Movement for Home-Based Therapy after Stroke. In: Proceedings of the 2004 IEEE Engineering in Medicine and Biology Society Meeting, San Francisco, California, September 1-5, pp 4787-4790.

T-WREX Counterbalance Efficacy Test

• 4 chronic hemiparetic subjects– moderate and severe arm impairment

• Therapist passively ranged affected and unaffected sides – 13 target locations at the workspace boundaries.

• 2 conditions – arm and device counterbalanced – only device counterbalanced

• Analysis: – Determine how much less force is needed to move the arm

when it is counterbalanced

Experimental Setup

Results

• Mean effect of gravity balance across 4 subjects. The circle radius is the magnitude of force required to hold the subjects’ arms at the 13 test fixture locations. The vertical bars indicate one standard deviation across subjects. (A) Impaired arm. (B) Unimpaired arm.

Testing of Effect on Movement Ability (while device is worn, in a single session)

• 9 Subjects tested:– chronic stroke ( > 6 months

prior), chosen since motor function is constant

– with persistent motor deficits.– exclusion criteria:

• cognitive deficits, neglect, and shoulder pain.

• Functional Test & 3 types of movement tests– performed with and without

gravity balance; subject always wore orthosis.

– randomized presentation.

Movement Tests

1. Functional Test: 14 tasks from the Fugl-Meyer Motor Function Test (Score range

0-28).

2. Reaching Movements: reached to targets located at the boundary of the arm’s passive workspace 8x, with affected arm.

– One contralateral, one ipsilateral target. – also reached upwards from the lap to the highest point

possible.

3. Drawing movement test: The subject traced circle patterns (diameter of 17.8cm) in the vertical plane, centered in front of them, 4-5 fist lengths from the front of the shoulder.

ContralateralIpsilateral

Results: Functional Test

• Subset of Fugl-Meyer Results out of possible 28 points:– without gravity-balance was 11.33 (+/- 6.3 SD)– with gravity-balance was 12.11 (+/- 6.2 SD)

• Average change in Fugl-Meyer Motor Function Test was:– 0.78(+/-1.3 SD).

• Change in Fugl-Meyer Motor Function Test – marginally significant (p = .055) for a one-sided, paired t-test

comparing the change to zero.

Results: Device expands range of motion

• Effect of gravity balance on reaching movements for 9 subjects. • A) Average reaching range of motion across subjects to targets

with and with out gravity balance (distance traveled to target/total distance to target).

• B) Average height reached above lap, with and without gravity balance.

• *p < .05, paired t-test.

Results: Circle Drawing

The ability to perform coordinated arm movement persistseven following 4.5 years of non-use, but is normally masked by gravity

T-WREX Preliminary Testing,Discussion

• Gravity balance provides assistive force above the horizontal reference but resists movement below

• Gravity balance improved:– a clinical measure of arm movement– range of motion of reaching movements– accuracy of drawing movements

• These results highlight the “threshold” nature of gravity:– strength is required to move against gravity – gravity balance appeared to unmask a latent motor coordination

capability that was not apparent with gravitational loading

• All subjects were pleased with their experience and asked to participate in future studies

Phase II: Pilot Study of T-WREX as a Motor Training System

Research question: Does regular movement practice with T-WREX

improve the ability to move the arm?

T-WREX, Java Therapy 2.0• Functional & Contextual games.

• Top: “To Do List”. Each subject practices playing 7 games for an assigned number of times.

• Bottom: Shopping Game. Subject uses a hand grip to pick up an item, moves it to the cart and releases their grasp to deposit the item.

• Other games: • Washing the stove• Eating• Cracking Eggs• Making Lemonade• Range of Motion• Washing your arm

T-WREX VIDEO

T-WREX Therapy Efficacy Testing • Entry criterion:

– minimum of 6 months post stroke– no shoulder pain– limited aphasia (must have been able to communicate pain)

• For the first 2wks, enough rubber bands were used to balance the arm in the horizontal position, level with the shoulder

• Rubber band counterbalance provided was as follows:– Weeks 1-2, 100%– Weeks 3-4, 80%– Weeks 5-6, 60%– Weeks 7-8, 60%

T-WREX Therapy Efficacy Testing, continued.

• Subjects received 4 clinical assessments before and after 8 weeks of therapy:1. Box and Blocks Test for Manual Dexterity (Mathiowetz et al.,

1985)2. Modified Box and Blocks3. Rancho Functional Test for The Hemiplegic /Paretic Upper

Extremity (Wilson et al., 1984)4. Fugl Meyer Motor Assessment (Fugl-Meyer et al., 1975)

• Subjects received 45min of movement training, 3x/week, for 8 weeks

• Changes in motor performance across each training session were measured by:– grip strength (prior)– the ability to reach to a target in three-dimensional space (prior)– the ability to reach to a target with the arm supported (prior)

Results: Functional and Impairment Tests

• DELTA is the difference of the post evaluation to the pre evaluation.

• †completed 15 of the 24 sessions. • *One sided t-test, p = 0.002.

Results: Impairment Score Detail

• Improvement in Fugl-Meyer Score As a Function of Joint at which improvement occurred and nature of Scoring Change

• A change from 0-1 indicates a change from unable to perform movement to able to perform partially, and a change from 1-2 is a change from performs partially to performs fully.

Results: Free Reaching Range

Mean percent range of motion across four subjects and three trials for 24 training sessions (Study Two). Percent range of motion was calculated by subtracting the mean distance traveled on the first day from the daily movements, then dividing the difference by the mean distance between the start point and target.

Results: Reaching Range and Grip Strength

• †completed 15 of the 24 sessions.• *significant regression, p < 0.05. • **One sided t-test, comparing change to zero, across all

therapy sessions, p < 0.05.

Results: Game Scores

Java Therapy game scores across the 24 training sessions (Study Two). Ensemble average of normalized game scores (possible range 0 to 1) for three games (Shopping, Ranging the Arm, and Cleaning the Stove) across the four subjects who completed all eight weeks of movement

training.

T-WREX Therapy Efficacy Testing, Discussion

• Subjects improved their arm movement ability with repetitive training with T-WREX

• Users of the device currently require about three minutes of assistance to don or doff

• Could allow a therapist to supervise several patients at a time for group therapy sessions, or possibly be used at home since it requires only minor assistance from a caregiver to use

• Ability to provide gradable levels of assistance make it well suited to customized training programs

• Ability to provide quantitative feedback of progress make it well suited for motivating motor training and for off-line monitoring of patient compliance and progress by a skilled rehabilitation therapist

Phase III Testing: Randomized Controlled Test of T-WREX’s

Efficacy

Research question: What are the benefits of regular movement practice

with T-WREX compared to a matched amount of conventional table top exercise

T-WREX Therapy Phase III Efficacy Testing

• Just started at RIC under the supervision of Sarah Housman, O.T.

• Subacute and chronic subjects (at least 2 months post-stroke)

• Random assignment to T-WREX or Control Group

• Blind rater

• Train 1 hour per session, 3 sessions per week, for eight weeks

• Limited interaction with therapist to simulate home or group therapy setting

• Expect to have tested ~25 subjects by this time next year, and ~ 50 by project end

T-WREX Therapy Phase III Efficacy Testing, continued.

• Entry criterion:– Minimum of 2 months post stroke – No shoulder pain– No significant cognitive impairments, hemispatial neglect, apraxia, or

aphasia– Presence of moderate/severe to severe UE hemiparesis

• Clinical assessments administered before and after therapy and 6 months after therapy is completed:1. Rancho Functional Test for The Hemiplegic /Paretic Upper Extremity

(Wilson et al., 1984)2. Fugl Meyer Motor Assessment (Fugl-Meyer et al., 1975)3. Grip Strength Testing with Jamar Hand Dynamometer4. Flock of Birds Motion Capture System5. UE Motor Activity Log

Phase III Testing: Randomized Controlled Test of T-WREX’s

Efficacy• Control Group completes conventional exercises that are

generally included in home exercise programs and group therapy sessions

A) Self Range of Motion

B) Active Assistive ROM

-C) Weight Bearing

-D) Use of hemiparetic arm in bilateral UE functional tasks

Other Future Directions• Robotic version of device – Pneu-WREX

• Design of a different arm support better suited to the specific needs of movement training after stroke

– adjustability (rubber bands are problematic)– shoulder internal/external rotation, supination/pronation

• Low-cost version – computer vision

• Commercialization?– Is there really a market?